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To quote bugzilla 143: 'package' does not work at all
But even if worked as advertised, it'd still be broken.
Although it's a really useful concept that works great in Java, the
existing 'package' doesn't fit with D's directory-based module system.
As I see it, the problem is that, given:
module first.second.third.fourth;
which package is this module part of?
Is it 'third', 'second.third', or 'first.second.third'?
I think that _all_ of those can be reasonable project designs; but the
compiler has no way of working out which is intended.
The behaviour currently described in the spec, that 'fourth' can use
functions defined in 'first', is a particularly odd choice. If they were
structs, the behaviour would be the exact opposite:
struct first {
struct second {
struct third {
int fourth;
}
}
}
then first could access fourth, but fourth couldn't reach second. I
think that's _generally_ the most sensible for modules, as well.
I think there are two possibilities:
(1) We work out some decent semantics for 'package'; OR
(2) We decide there isn't time, and defer it to D3.
Maybe the solution is a simple as adding a 'package' field to the module
declaration. (eg,
module first.second.third.fourth package first.second;
)
But I fear that a major change to the module system might be required,
which wouldn't be viable at this late stage.
Option (2) is possible because 'package' has never actually worked. It
seems to be just a synonym for 'public' at present. Clearly, we can
survive without it, no matter how desirable it is.

On Fri, 20 Nov 2009 19:52:09 +0300, Don <nospam@nospam.com> wrote:
> To quote bugzilla 143: 'package' does not work at all
>
> But even if worked as advertised, it'd still be broken.
>
> Although it's a really useful concept that works great in Java, the
> existing 'package' doesn't fit with D's directory-based module system.
> As I see it, the problem is that, given:
>
> module first.second.third.fourth;
>
> which package is this module part of?
> Is it 'third', 'second.third', or 'first.second.third'?
>
> I think that _all_ of those can be reasonable project designs; but the
> compiler has no way of working out which is intended.
> The behaviour currently described in the spec, that 'fourth' can use
> functions defined in 'first', is a particularly odd choice. If they were
> structs, the behaviour would be the exact opposite:
>
> struct first {
> struct second {
> struct third {
> int fourth;
> }
> }
> }
> then first could access fourth, but fourth couldn't reach second. I
> think that's _generally_ the most sensible for modules, as well.
>
> I think there are two possibilities:
> (1) We work out some decent semantics for 'package'; OR
> (2) We decide there isn't time, and defer it to D3.
>
> Maybe the solution is a simple as adding a 'package' field to the module
> declaration. (eg,
> module first.second.third.fourth package first.second;
> )
> But I fear that a major change to the module system might be required,
> which wouldn't be viable at this late stage.
>
> Option (2) is possible because 'package' has never actually worked. It
> seems to be just a synonym for 'public' at present. Clearly, we can
> survive without it, no matter how desirable it is.
I never felt a need for "package" module attribute. But at class
protection level, package implying final is ... ouch!

Don wrote:
> To quote bugzilla 143: 'package' does not work at all
>
> But even if worked as advertised, it'd still be broken.
>
> Although it's a really useful concept that works great in Java, the
> existing 'package' doesn't fit with D's directory-based module system.
> As I see it, the problem is that, given:
>
> module first.second.third.fourth;
>
> which package is this module part of?
> Is it 'third', 'second.third', or 'first.second.third'?
>
> I think that _all_ of those can be reasonable project designs; but the
> compiler has no way of working out which is intended.
> The behaviour currently described in the spec, that 'fourth' can use
> functions defined in 'first', is a particularly odd choice. If they were
> structs, the behaviour would be the exact opposite:
>
> struct first {
> struct second {
> struct third {
> int fourth;
> }
> }
> }
> then first could access fourth, but fourth couldn't reach second. I
> think that's _generally_ the most sensible for modules, as well.
>
> I think there are two possibilities:
> (1) We work out some decent semantics for 'package'; OR
> (2) We decide there isn't time, and defer it to D3.
>
> Maybe the solution is a simple as adding a 'package' field to the module
> declaration. (eg,
> module first.second.third.fourth package first.second;
> )
> But I fear that a major change to the module system might be required,
> which wouldn't be viable at this late stage.
>
> Option (2) is possible because 'package' has never actually worked. It
> seems to be just a synonym for 'public' at present. Clearly, we can
> survive without it, no matter how desirable it is.
Well put.
I think we can just drop "package" and adopt a similar model to that of
Go with D modules. it looks simple and flexible. especially the ability
to have a Go package span several files.

On Fri, 20 Nov 2009 18:52:09 +0200, Don <nospam@nospam.com> wrote:
> module first.second.third.fourth;
> which package is this module part of?
> Is it 'third', 'second.third', or 'first.second.third'?
Perhaps you meant: 'first', 'first.second', or 'first.second.third'?
The case you mention presents an immediate ambiguity, but it is clarified
by the module declaration or on the first import. If 'first.second.foo'
imports 'first.second.third.bar' by 'import third.bar', and
'first.second.third.bar' has a module declaration or is imported from
somewhere else using a different package "path", the compiler will
generate an error ("Error: module X is in multiple packages Y")
--
Best regards,
Vladimir mailto:thecybershadow@gmail.com

Vladimir Panteleev wrote:
> On Fri, 20 Nov 2009 18:52:09 +0200, Don <nospam@nospam.com> wrote:
>
>> module first.second.third.fourth;
>> which package is this module part of?
>> Is it 'third', 'second.third', or 'first.second.third'?
>
> Perhaps you meant: 'first', 'first.second', or 'first.second.third'?
>
> The case you mention presents an immediate ambiguity, but it is
> clarified by the module declaration or on the first import. If
> 'first.second.foo' imports 'first.second.third.bar' by 'import
> third.bar', and 'first.second.third.bar' has a module declaration or is
> imported from somewhere else using a different package "path", the
> compiler will generate an error ("Error: module X is in multiple
> packages Y")
How do you define module fourth so that its 'package' functions are
accesssable only to modules in first.second.* and not in first.* ?

Don wrote:
> Vladimir Panteleev wrote:
>> On Fri, 20 Nov 2009 18:52:09 +0200, Don <nospam@nospam.com> wrote:
>>
>>> module first.second.third.fourth;
>>> which package is this module part of?
>>> Is it 'third', 'second.third', or 'first.second.third'?
>>
>> Perhaps you meant: 'first', 'first.second', or 'first.second.third'?
>
>
>>
>> The case you mention presents an immediate ambiguity, but it is
>> clarified by the module declaration or on the first import. If
>> 'first.second.foo' imports 'first.second.third.bar' by 'import
>> third.bar', and 'first.second.third.bar' has a module declaration or
>> is imported from somewhere else using a different package "path", the
>> compiler will generate an error ("Error: module X is in multiple
>> packages Y")
>
> How do you define module fourth so that its 'package' functions are
> accesssable only to modules in first.second.* and not in first.* ?
>
You don't. The package in this case should be first.second.third and
that's that. That's how it works in Java and is sometimes quite useful.

Don wrote:
> To quote bugzilla 143: 'package' does not work at all
>
> But even if worked as advertised, it'd still be broken.
>
> Although it's a really useful concept that works great in Java, the
> existing 'package' doesn't fit with D's directory-based module system.
> As I see it, the problem is that, given:
>
> module first.second.third.fourth;
>
> which package is this module part of?
> Is it 'third', 'second.third', or 'first.second.third'?
>
...
Assuming you meant first, first.second and first.second.third, I'd say the
most sensible choice is first.second.third (I actually assumed it works this
way already).
Why? Currently the most coarse level of granularity (excluding package) that
has any meaning in D is the module level. If you want 'friend' access one
step beyond that it only makes sense to choose the modules that map to the
same directory. I'd like to think that is more than enough exposure for
anyone.
Anything beyond that seems way too promiscuous to me, like a poor substitute
for C++'s friend.